A light emitting diode (LED) is a solid semiconductor light emitting device. With the advancement of LED technology, the LED package is developing towards near-ultraviolet range and even deep-ultraviolet range as well as high power. However, in a typical conventional package, the LED chip surface is coated with a layer of high-refractivity organic package adhesive, which is prone to failure after long-term service due to such factors as water, light and heat. This leads to sharp depreciation of device luminous flux and radiant flux, and even causes device failure. For high-power LED integrated light sources, a variety of factors like chip heating and insufficient heat dissipation may result in high surface temperature and device failure.
Currently, most UVLEDs are in the range of UVA and UVB. Typically, UVA covers the range of 320-400 nm, and is also known as long-wavelength black-light ultraviolet. With strong penetration, UVA can penetrate deeply into most glass and plastic; while UVB covers the range of 275-320 nm, and is also referred to as middle-wavelength red-light ultraviolet. UVB exhibits medium penetration, and its short-wavelength part can be absorbed by transparent glass.